OIL AND GAS ACCUMULATION AND EXPLORATION POTENTIAL INTHE SHENGSHUN OILFIELD, THE BOHAI SEA

The Shengshun Oilfield lies on the east slope of the Bodong Sag. No obvious progress has been made during the last decade in oil and gas exploration and the exploration potential and direction remain a puzzle. How to break the deadlock is a key issue we are facing. There are four sets of reservoir-cap assemblages in the region based on the analysis of faults, traps and hydrocarbon accumulation conditions in different strata. Although the Proterozoic structural trap is widely distributed, the reservoir is serious heterogeneous and structure complicated, it might be considered as a subordinate choice in exploration. The Member Sha 4 to Kongdian Formation is a kind of typical residual deposits, which mainly consists of igneous rock debris with poor physical properties. The Dongying Formation and Guantao Formation are the main exploration targets after an overall evaluation. Influenced by strike-slip faults, the structural traps in the Formations usually have low oil-bearing height and small oil-bearing area. However, the stratigraphic overlap traps and fault-lithology traps are of relatively large exploration potential. Within the system, the unconformity under the Dongying Formation may provide a pathway for lateral migration and the strike-slip fault control the vertical hydrocarbon movement. The NNE oil source faults, plus the unconformity and the NWW faults make of a three dimensional ladder-like migration network. According to this model, exploration close to source should be prioritized in the region.